SQUID-based Readout Systems for Cryogenic Dark Matter Detectors

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A broad range of observations tell us that about 85% of the matter in the universe is not made of ordinary particles, but exists in some dark form. Deciphering the nature of this dark matter is of fundamental importance to cosmology, astrophysics, and particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles (WIMPs) that were produced moments after the Big Bang. Such particles would represent an extension of the Standard Model of particle physics, such as supersymmetry or additional dimensions. If WIMPs exist and are the dark matter, then their presence in our Milky Way may be detectable via scattering from atomic nuclei in a terrestrial detector. The Cryogenic Dark Matter Search (CDMS) Collaboration has pioneered the use of low-temperature phonon-mediated devices to detect the rare scattering of WIMPs on nuclei and to distinguish these events from other background interactions. One of many key technological requirements for the scaling to greater mass of the low-temperature germanium technology is improvement in the cryogenic preamplifiers of both phonon and ionization signals. The superconducting quantum interference device (SQUID) preamplifiers used in the present Soudan facility were produced and evaluated through the efforts of this group several years ago, and the group has been an integral member of the collaboration in optimizing their performance throughout the operation of the various CDMS experiments at Soudan. This award will support the scientific aspects of the CDMS programs in four complementary directions, fully coordinated within the collaboration: (a) support of the SuperCDMS-Soudan experiment (participating in operation of the Soudan experiment, particularly oversight and maintenance of the phonon readout system), (b) contribution to the design of SuperCDMS-SNOLAB (design optimization of cold hardware and electronics), (c) scientific support to SuperCDMS-SNOLAB construction (production testing of SuperCDMS-SNOLAB SQUIDs and room-temperature electronics), and (d) long-term R&D towards GEODM (SQUID-based ionization readout). Continued development of the cryogenic readout systems is a critical component of the science goals of the SuperCDMS and GEODM programs.Broader ImpactsThis program's technological development will also push the envelope of phonon-mediated detectors, the applications of which are increasingly widespread. This program will also support the education and training of physics and electrical engineering students.